Question

Find the volume and surface area of a sphere of radius $21 \mathrm{~cm}$.

Answer 1

Solution-

Radius of the sphere $=21 \mathrm{~cm}$.

Volume of the sphere $=\left(\frac{4}{3} \pi r^{3}\right)$ cubic units

$$

\begin{array}{l}

=\left(\frac{4}{3} \times \frac{22}{7} \times 21 \times 21 \times 21\right) \mathrm{cm}^{3} \\

=38808 \mathrm{~cm}^{3} .

\end{array}

$$

Surface area of the sphere $=\left(4 \pi r^{2}\right)$ sq units

$$

=\left(4 \times \frac{22}{7} \times 21 \times 21\right) \mathrm{cm}^{2}=5544 \mathrm{~cm}^{2} \text {. }

$$